I am a total noob to plugins so forgive me if I am asking about something obvious.

I always assumed that Raid Assistant or similar plugins had meters on screen that showed how much threat/damage/healing each member of the group was doing, so say, at the end of a boss fight you could see how the group had performed.

Looking at the features of Raid Assistant, it doesn't seem that is part of it. So is my assumption completely wrong or am I just looking at the wrong plugin?

However functionality of that plugin in LOTRO is not as wide as you might expect if you used such tools in other games; it can track your characters Damage Done, DPS, Healing Done, Healing Received, and events like stuns/mezzes etc; but it cannot track Threat, will have trouble tracking damage absorb shields you put on other players. Also what can be tracked can be tracked for your character only, not other group members.